The invention relates generally to lower or drive units of marine propulsion devices, such as outboard motors and stern drive units. Still more particularly, the invention relates generally to gear cases incorporated in such lower units and to the shapes or configurations of such gear cases. Still further in addition, the invention relates to shapes or configurations which are intended to affect the operation of such marine propulsion devices and which affect the back pressure in the exhaust gas discharge passage in through the hub exhaust gas systems in stern drive and outboard motors.
Attention is directed to the following U.S. Pat. Nos.:.
______________________________________ 3,554,665 Lorenz, et al. January 12, 1971 3,727,574 Bagge April 17, 1973 3,939,792 Wasenius February 24, 1976 3,939,795 Rocka February 24, 1976 4,080,099 Snyder March 21, 1978 4,096,819 Evinrude June 27, 1978 4,295,835 Mapes, et al. October 20, 1981 4,447,214 Henrich May 8, 1984 4,898,553 Bankstahl February 6, 1990 4,911,665 Hetzel March 27, 1990 ______________________________________
With respect to the above patents, attention is particularly directed to FIG. 5 of U.S. Pat. No. 4,295,835.